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A193453 Number of odd divisors of phi(n). 3
1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 2, 1, 2, 2, 1, 1, 1, 2, 3, 1, 2, 2, 2, 1, 2, 2, 3, 2, 2, 1, 4, 1, 2, 1, 2, 2, 3, 3, 2, 1, 2, 2, 4, 2, 2, 2, 2, 1, 4, 2, 1, 2, 2, 3, 2, 2, 3, 2, 2, 1, 4, 4, 3, 1, 2, 2, 4, 1, 2, 2, 4, 2, 3, 3, 2, 3, 4, 2, 4, 1, 4, 2, 2, 2, 1, 4, 2, 2, 2, 2, 3, 2, 4, 2, 3, 1, 2, 4, 4, 2, 3, 1, 4, 2, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,7

COMMENTS

phi(n) : A000010 is the Euler totient function. This sequence equals A193169 (n) for n < 63.

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..16384

FORMULA

a(n) = A001227(A000010(n)) = A000005(A053575(n)). - Antti Karttunen, Dec 04 2017

EXAMPLE

a(63) = 3 because phi(63) = 36 with 3 odd divisors {1, 3, 9}.

MATHEMATICA

f[n_] := Block[{d = Divisors[EulerPhi[n]]}, Count[OddQ[d], True]]; Table[f[n], {n, 80}]

PROG

(PARI) A193453(n) = sumdiv(eulerphi(n), d, d%2); \\ Antti Karttunen, Dec 04 2017

CROSSREFS

Cf. A000010, A001227, A053575.

Sequence in context: A055734 A295660 A193169 * A227944 A095772 A305392

Adjacent sequences:  A193450 A193451 A193452 * A193454 A193455 A193456

KEYWORD

nonn

AUTHOR

Michel Lagneau, Jul 26 2011

EXTENSIONS

More terms from Antti Karttunen, Dec 04 2017

STATUS

approved

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Last modified October 22 18:45 EDT 2021. Contains 348175 sequences. (Running on oeis4.)